In a conventional mobile telecommunication system, like UMTS, the primary station like a base station (or NodeB) and the secondary stations, like the mobile stations communicate together by means of a plurality of channels. Mainly, when the primary station wishes to transmit data to a secondary station, the primary station signals to the considered secondary station that data will be transmitted, and in which block of physical resource this data has been allocated. A block of physical resource can be a time slot, and/or a frequency subcarrier, and/or a code.
In the UMTS Long Term Evolution (LTE), the downlink data can be transmitted on the Physical Downlink Shared Channels 10 (PDSCHs), illustrated on FIG. 1. Downlink time-frequency resources 12 containing a data transmission for a secondary station on the PDSCH are signalled by a signalling message on a control channel 11 (PDCCH—Physical Downlink Control Channel) transmitted immediately before the PDSCHs 10.
Consequently, each secondary station needs to buffer all the PDSCHs 10 across the full system bandwidth until it has decoded the PDCCH 11, in case there is some data for it on one of the PDSCHs 10. This is represented on FIG. 1 by interval T. As a consequence, each secondary station needs to keep its receiver switched on while it decodes the control channel PDCCH 11. This leads to an energy consumption and thus reduces the battery life of the secondary stations.
While this may not be a significant problem when continuous or high-rate data is being transmitted to a secondary station, it can result in significant unnecessary energy usage when the secondary station is not receiving data frequently, since it has to receive data that may be useless during the interval T in each subframe.